What about those with MDD who actually have genetic and biological components happening here? This is implying that negative imagery is causative of PTSD or depression but these two diseases are very much physiological diseases. Both sufferer's are undergoing a major internal stress response inside the body whether it was triggered by a physical or emotional event. There are a multitude of factors that play into these very complex diseases. I can see this maybe being helpful for mild depression but this type of therapy ignores too many other components that are calculated in MDD and PTSD.